Gradius is a popular series of horizontal-scrolling shooter games developed by Konami. Its main protagonist is a ship called the Vic Viper. One of its signature enemies is the Moai, an alien space construct based on the real-life Easter Island Moai, which shoots rings of energy. Castlevania has made several references to the Gradius series.
References to the Gradius series in Castlevania games are as follows:
- The Moai was a collectible item worth 4,000 points in the original Castlevania game. It later returned in Castlevania Chronicles and Curse of Darkness.
- One of Vic Viper's signature items is a set of star-shaped shields which appear in front of it and which get smaller each time they're hit. This shield also appeared in Symphony of the Night and is created with a special ability of the Shield Rod.
- The special name entry to enter Magician Mode in Circle of the Moon is "GRADIUS".
- The Vic Viper shield returns in Harmony of Dissonance when the Bolt Book and Holy Book spell fusion is used.
- The Moai returned in Curse of Darkness if you had a save from Lament of Innocence on your memory card. It could be sold at a high price or could be used to replenish all of your health.
- The ship of the Gradius series, Vic Viper, appears as a reward item in Portrait of Ruin.
- The Bat Company boss from Dawn of Sorrow shape-shifts into different forms, one of which is a Moai head, complete with the energy ring attack.
- Order of Ecclesia has three references to Gradius:
Mascot games which contain both Castlevania and Gradius characters:
- Vic Viper and Moai can race against Dracula in Konami Krazy Racers.
- Vic Viper can fight side-by-side with Kid Dracula in Gokujō Parodius! ~ Kako no Eikō o Motomete ~ and Jikkyō Oshaberi Parodius ~ forever with me ~.
- Vic Viper and fellow ships Lord British, Option, Multiple and Black Viper, can fight through Dracula's Castle and battle against a giant Medusa in the Gradius parody game Sexy Parodius.
- Vic Viper and Moai can help Simon Belmont in Konami Wai Wai World.
- Vic Viper can fight alongside Simon Belmont in Wai Wai World 2: SOS!! Parsley Castle and Konami Wai Wai Sokoban.
- Moai can play mahjong against Simon Belmont in Hai No Majutsushi.
- Moai can fight against Simon Belmont in DreamMix TV: World Fighters.
Production similarities between Castlevania and Gradius:
- The ending of Gradius II: GOFER no Yabou (PC Engine) lists Castlevania series producer Koji Igarashi as a programmer.
- The album Konami Game Music Collection Volume 1 contains music from Haunted Castle and Gradius II: GOFER no Yabou among other games.
- The album MIDI Power 3 contains midi arrangements for both the Sharp X68000 version of Castlevania and Gradius III.
- The first entry in Konami's "ReBirth" series of WiiWare games was Gradius ReBirth. This was later followed up with Castlevania: The Adventure ReBirth.